Resuscitator valve assembly



P 0 M. ISAACSON 2,952,265

RESUSCITATOR VALVE ASSEMBLY Filed Feb. 8, 1956 FIG.Z

FIG. 3

IN V EN TOR.

MAX ISAACSON ms A-rronnevs United States Patent RESUSCITATOR VALVEASSEMBLY Max Isaacson, Dayton, Ohio, assignor to Globe Industries, Inc.,a corporation of Ohio Filed Feb. 8, 1956, Ser. No. 564,167

8 Claims. (Cl. 137-64) This invention relates to a pressure controlapparatus for resuscitators and the like, and more particularly to animproved valve assembly therefor, although not necessarily so limited.

The pressure control apparatus of this invention is designed for use inresuscitators operating from a source of gas under pressure, the controlapparatus including an aspirator assembly or venturi tube for producinggas pressures less than the pressure of the ambient atmosphere, that is,negative pressures. The resuscitator breathing cycle, comprisingsuccessive intervals of positive and negative pressure produced in thecontrol apparatus, is regulated by intermittently opening and closingthe aspirator assembly with a valve mechanism. In the operation of thisvalve mechanism, the efliciency of the valve action regarding absence ofleakage and the energy required for operation is of critical importance.

An object of this invention is to provide a valve assembly' constructedfrom light weight parts for use in resuscitators, which assembly can beactuated with a minimum of effort by a' reciprocating member movingthrough a relatively short stroke.

Another object of this invention is to provide a valve assemblyemploying a self-sealing flexible reed member as a slide valve, so as toprovide positive valving action.

Still another object of this invention is to provide a valve assemblyfor alternately opening and closing an aspirator tube, which valve islocated so as not to obstruct the flow of gas in the tube when theaspirator tube is open.

Other objects and advantages reside in the construction of parts, thecombination thereof and the mode of operation, as will become moreapparent from the following description.

In the drawings,

Figure 1 is a top plan View of the pressure control apparatus of thisinvention, with parts broken away.

Figure 2 is a sectional view taken substantially along the line 22 ofFigure 1.

Figure 3 is a perspective view of the pressure control apparatus, withparts broken away.

Figure 4 is a top plan view of a modification of this invention, withparts broken away.

The resuscitator to which this invention applies utilizes a source ofgas under pressure as a means of forcing a patient to inhale and anaspirator through which the gas under pressure flows as a means ofwithdrawing the gas from the lungs of the patient for exhalation. In theconstruction of such a resuscitator, it is common practice to connectthe source of gas to the aspirator, providing a connection between anopening in the aspirator and the patients lungs, and to provide abutterfly valve or the like in the aspirator, downstream from theopening, for opening and closing the downstream portion of the aspiratorassembly. When the valve is in the closed position, the aspirator isinoperative and gas under pressure flows out of the aspirator opening tothe patients lungs. When the valve is in the open position,

the aspirator is operative and gas is withdrawn from the patients lungsthrough the aspirator opening.

The present invention resides in a novel valve and aspiratorconstruction and arrangement whereby the fluid flow through theaspirator is unobstructed when the resuscitator is operating to producea negative pressure and whereby the fluid flow into the aspirator isutilized as an aid in seating a valve which substantially completelyshuts off the fluid flow through the downstream portion of the aspiratorwhen the resuscitator is operating to produce a positive pressure.

Referring to the drawings in greater detail, a cylindrical housing 10houses the pressure control apparatus of this invention. The housing 10is formed from two mating cup-shaped members 12 and 14 separated by aflexible, radially disposed circular membrane or diaphragm 16. Themarginal portion 18 of the diaphragm 16 provides a sealing gasketbetween the two members 12 and 14 which are held in compressiveengagement therewith by suitable clasps (not shown).

Thehousing 10 is thus divided into two chambers 20' and 22, the latterbeing maintained air-tight and the former being open to the ambientatmosphere, as will be described subsequently.

An aspirator assembly, comprising two axially aligned conduit members 24and 26, traverses the housing member 14 in the chamber 22. The conduitmembers 24 and 26 are held in fixed spaced relationship by a thinsegmental wall portion 28 to provide an opening or spill port 30therebetween.

The conduit member 26, representing the downstream portion of theaspirator assembly, connects to the ambient atmosphere through the wallof the housing member 14 and through a block 36 integral with thehousing member 14.

The conduit member 24, representing the upstream portion of theaspirator assembly, connects to a jet injection device 40 through thewall of the housing member 14. The jet injection device is provided withan adapter 44 for connection to a source of gas under pressure, as, forexample, a cylinder of compressed oxygen or air. Preferably, the jetinjection device is equipped with means (not shown) for adjusting theflow of gas through the jet and with means (not shown) for diluting thegas stream with air when this is desired.

In the operation of the aspirator assembly, gas is injected in a jetstream into the upstream conduit member 24 by the jet injection device40. As shown in the drawings, a thin flexible reed-like valve member 46closes the conduit member 26. The gas, traveling through the conduitmember 24, impinges upon the valve member 46 and is deflected into thechamber 22. The chamber 22 connects through a coupling member 38supported by the block 36, and through a face mask or breathing tube(not shown) to the lungs of a patient. The chamber 22, coupling member38, face mask or the like, and the patients lungs represent a closedvolume which is filled by the gas delivered by the conduit member 24.

By a mechanism to be described subsequently, the valve member 46 ispivoted to open the conduit member 26 when the gas pressure in theclosed volume reaches a critical maximum value. The gas stream,traveling through the conduit 24, then no longer deflected by the valvemember 46, crosses the spill port 30 to enter the conduit member 26which has a tapered channel 34 passing therethrough.

The flow of gas from the smaller conduit member 24 into the taperedchannel 34 creates a low pressure zone at the mouth of the conduitmember 26. As a result, gas is evacuated from the chamber 22 through theconduit 26. This reduces the pressure in the closed volume including thechamber 22. When the gas pressure drops sufiiciently below that'of theambient atmosphere, the valve member 46 is reseated on the conduitmember 26, to reinitiate an inhalation cycle.

In this manner, the aspirator assembly is employed to provide a cyclicrising'and falling pressure in the closed volume including the chamber22. The mechanism for actuating the valve member 46 operates as follows.

The rising and falling pressure in the chamber '22 tends to move thediaphragm 16 axially in the housing 14;, so as to increase or decrease'the volume of the chamber 22. The axial motion of the diaphragmispromoted by pro viding a pair of oppositely directed annular arches 48adjacent the'cylindrical wall of the housing 1! which enable the centralportion ofthe diaphragm to move axially without stretching. The centralportion of the diaphragm is further prevented from bowing or stretchingby providing a thin disc as of metal or plastic, or the like, on eitherside thereof. The discs may be secured to the diaphragm by anelastomeric grommet 52, as shown, or by any other suitable means.

A rod 54 extends axially through the housing and the grommet 52, the rod54 passing through apertures 56 provided therefor in the end walls ofthe housing. The grommet 52 compressively engages the rod 54 to providean air-tight seal between the rod and the diaphragm. Oppositelydirected'coil'springs 5&secured to the rod 5% bywashers'fithcornpres'sively abut the disc'siitl on either side of thediaphragm to yieldingly secure-the diaphragm 16 to the rod 5 4. The rod54 is thus "urged to move axially by the diaphragm 16 when the pressureis the chamber 22 rises or falls.

Secured non-rotatably to opposite ends of the rod 54 are bars offerro-magnetic material, such as iron, forming armatures 62 and 64extending normal to the axis of the rod. The two armatures 62 and 64 aredisposed in parallel relationship. Annular flanges 66 projecting axiallyfrom each end of the housing 11 provide cylindrical cavities, one ateach end of the housing 119, into which are press-fitted ring magnets,there being one ring magnet 68 at one end of the housing 1% adjacent thearmature 62, and another ring magnet 70 at the opposite end of thehousing 10 adjacent the armature 64. The two ring magnets 68 and 70 areso oriented that the magnetic field in one is parallel to the magneticfield in the other.

The length of the rod 54 is such that when the armature 62 is in contactwith the adjacent magnet 68 at one end of the rod, the armature 64 andthe magnet 7% at the opposite end of the rod are spaced apart. When aforce is exerted upon the rod 54, so as to move the armature 62 axiallyaway from the magnet 68, as may be exerted by the diaphragm 16 when thepressure in the chamber 22 rises, movement of the armature 62 away fromthe magnet 68 is opposed by the magnetic field therebetween until thearmatures 62 and 64 are equally spaced from their respective magnets 68and 79 a neutral point. With continued axial movement of the rod 54, theattractive force between the magnet 76 and the armature 64 becomesdominant and the rod 54 is accelerated by the magnetic field until thearmature 64 contacts the magnet 7%. Thus, as the pressure in the chamber22 rises or falls, movement of the diaphragm 16 is at first opposed orrestrained by the magnets, then subsequently accelerated by the magnets.

In the operation of this restraining mechanism, a finite pressure mustbe developed in the chamber 22 before the armature 62 can be separatedfrom the magnet 66. As this critical pressure is approached, theopposing springs 53 are displaced slightly by the diaphragm 16. At theinstant the armature 62 separates from the magnet 68 under the influenceof rising pressure in the chamber 22, the energy stored in the springs58 is released, this energy being sumcient to throw the rod 54, carryingthe armatures 62 and 64, past the neutral point, so that the armature64, attracted by the magnet 70, moves into contact therewith.

The combined forces of the magnets 68 and 70 and the springs 58 aresuflicient to throw the rod 54 from one extreme axial position in thehousing 10 to an opposite extreme position in the housing 10 after thepressure in the chamber 22 has reached a critical minimum value.Similarly, if the pressure in the chamber drops sufficiently below thepressure of the ambient atmosphere, the rod 54 is thrown to the reverseextreme position by the combined action of the springs 58 and themagnets -68 and 7%. There is no stable position of the rod 54-interrnediate the extreme axial positions thereof.

Clearl the maximum and minimum pressures required to actuate the rod 54are determined by the strength of magnetic attraction between thearmatures and the magnets. When the armatures are aligned in parallelrelation with the north and south poles of the ring magnets, themagnetic attraction is at a maximum and, when the armatures are disposednormal to the poles of the ring magnets, the attraction isat a minimum.By rotating the armatures 62 and 64 relative to't'he magnets 63 and 7d,the critical gas pressures required to actuate the rod 5d may be varied.

Rotation of the armatures is provided for in the following: A cap 72 isrotatably secured to the annular flange 66 integral with the'member 12.A flange 74, depending from the cap 72, engages the side of the armature62, so that both the armature 62 and the armature 64 may be rotated byrotating the cap 72. The flange '74 in no way restricts the axial motionof the armature 62. Preferably, the cap 72 and flange 74 are fabricatedfrom a paramagnetic material, such as aluminum, so as not to interfereappreciably with the magnetic interaction between the armature 62 andthe magnet 68.

A pointer 76, locatedcxternal to the cap 72, indicates the relativeposition of the armature. A scale (not shown) may be placed on thehousing 10 to facilitate positioning of the armatures. A similar cap 78is press-fitted, or otherwise secured, to the flange 66 at the oppositeend of the housing 10, to provide an air-tight closure for isolating thechamber 22 from the ambient atmosphere. A hole 79 is placed in the wallof the housing member 12, so as to provide a direct connection betweenthe chamber 20 and the ambient atmosphere.

The reciprocating snap action of the rod 54 is employed to actuate thevalve member 46 situated in the chamber 22 as follows. Rotatably securedto the rod 54 is an actuator member 80, which moves axially therewith.Rotation of the actuator member Si) is restricted by a substantiallyL-shaped bracket having one leg 82 secured to a projection 84 integralwith the housing member 14 by means of a screw 36. The other leg 88 ofthe bracket has an axially extending slot 90 therein, into which an arm2 of the actuator member projects. The slot 9% permits axial movement ofthe actuator member, but restricts rotary movement of the actuatormember.

At one end of the valve member 46 an integral flange portion is archedor folded over to provide a substantially -U-shaped portion 94, the legsof which are apertured to accommodate a pin 96. The pin 96, journalledto the U-shaped portion 94, is secured to aflange 9% pro jectingnormally from the leg 82 of the Lshaped bracket member. The valve member46 is thus pivotally secured to the L-shaped bracket member. The legs ofthe Ushaped portion 94 are freely or slightly yieldingly disposedbetween the flange 98 on one side and an enlarged portion 1% of the pin96 on the other side, so that the valve member 46 is self-aligning uponthe pin 96 and relatively freely pivoted for opening and closing thedownstream portion or inlet opening of the conduit 26.

The actuator member 80 is provided with an arm 102 for engaging thevalve member 4 6, the arm MP2 projecting into an aperture 124 providedtherefor in the valve member 4'6. Substantially triangular tongueportions 106, integral with the valve member 46, project oppositely intothe aperture 104 to provide knife edges for engagement with the actuatorarm 102.

As the rod 54 and actuator member 80 undergo reciprocal motion, theactuator arm 102 engaging the valve member 46 causes the valve member topivot about the pin 96. The unsupported end of the valve member 46projects into the spill port 30 of the aspirator assembly, to seat uponthe end of the conduit member 26 which is finished to provide a flatvalve seat.

The reciprocating snap action of the rod 54, created by rising andfalling pressure in the chamber 22, causes the actuator arm 102 to pivotthe valve member 46 between extreme pivotal positions, .the valve member46 acting as a slide valve opening and closing the conduit member 26.The arrangement and size of parts is such that as the rod 54reciprocates between extreme positions, the valve member 46 fully opensor fully closes the conduit member 26. Y

The rate of intermittent cycling is determined by the rate of flow ofgas from the injection device into the aspirator assembly in proportionto the closed volume of thechamber 22, lungs, et cetera. Clearly, anyleaks in the closed volume will-prolong the inhalation cycle. It is thusparticularly important that the valve member 46 be firmly seated uponthe conduit member 26 during the inhalation cycle, to provide aleak-proof closure. The valve member 46, due to its flexible reed-likeconstruction, is particularly effective for this purpose, the valvebeing self-sealing under the influence of the impinging air stream.

7 It is preferable that a resuscitator apparatus have the capacity foroperating at low pressure amplitudes, so as to provide a very gentlebreathing action when this is desired. As was indicated previously, thepressure amplitude required for actuating the rod 54 is determined bythe restraining forces exerted by the magnets 68 and 70. Thisrestraining force is augmented somewhat by friction and inertia in thevalve assembly. The valve assembly of this invention is designed tooperate with a minimum of friction between parts and with a minimum ofinertia, the design lending itself particularly to the use of lightweight elements. In this construction, the weight of the actuator member80 and the valve member 46 may be made negligible in comparison to therestrainin-g forces exerted by the magnets 68 and 70. The valve member46 may be, for example, a thin piece of metal or plastic, or the like.The valve member 46 illustrated herein is made of stainless steel, themember being .a few thousandths of an inch in thickness.

The valve assembly is also particularly well suited to a short stroke ofthe rod 54 which is necessary for proper functioning of the-magnetrestraining assembly. The length of the stroke required of the rod isapproximately one-half that required of the unsupported end of the valvemember 46.

Figure 4 illustrates a modification of the preferred embodimentdescribed in Figures 1-3. It will be noted in connection with thepreferred embodiment, that the jet injection device 40 and aspiratorassembly operate in combination to provide a pair of jets in tandem,there being one gas jet in the jet injection device and a second gas jetat the downstream end of the conduit 24. The first jet may 'be employedfor air dilution of the gas by creating an aspirator effect in the jetinjection device or for any other resired purpose. The second jet isused as described for evacuating the patients lungs in forced exhalationin connection with the resuscitator operation.

In Figure 4, a modified resuscitator embodying only a single jet isshown. In this modification,-the aspirator assembly traversing thehousing member 14 includes a modified jet injection device 110 and asingle conduit member 112 traversing the chamber 20 in axial alignmentwith the jet injection device. The conduit memher 112 has a taperedchannel portion 114 therein communicating with ambient atmosphere.

The end of the conduit member 112 adjacent the jet injection device 110is machined to provide a valve seat for accommodating a pivotallymounted slide valve member. The valve member and mechanism for operatingthe valve member so as to open and close the conduit member 112 issbstantially the same as that of the preferred embodiment with minorchanges in the construction and arrangement of parts.

The leg 88 and the flange 98 of the L-shaped bracket member of thepreferred embodiment are interchanged in the modification of Figure 4 soas to relocate the valve member 46. As in the preferred embodiment, thevalve member 46 is pivotally secured to the flange 98 of the L-shapedbracket member. The actuator member is pivoted 180 on the rod 54 sothat, as in the preferred embodiment, the actuator member 80 movesslidably in the slot of the leg 88 of the L-shaped bracket member. Thearm 102 of the actuator member 80 engages the valve member 46 as in thepreferred embodiment.

The mechanism for operating the valve member 46 so as to open and closethe conduit member 46 is otherwise the same as that of the preferredembodiment. Again, the incoming gas stream from the jet injection deviceis utilized as an aid in firmly seating the valve member 46 upon the endof the conduit member 112.

Although the preferred embodiment and a modification of the device havebeen described, it will be understood that within the purview of thisinvention various changes may be made in the form, details, proportionand arrangement of parts, the combination thereof and mode of operation,which generally stated consist in a device capable of carrying out theobjects set forth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. A cycling valve apparatus for breathing equipment having a fluidreceiving chamber enclosed by a pressure sensitive means; an outletdelivery conduit member connecting said chamber for periodicallydelivering fluid therefrom; an aspirator assembly associated with saidchamber for periodically evacuating fluid from said chamber, saidaspirator assembly comprising an aspirator conduit provided with aninternal restriction for creating a jet stream of fluid to aid saidevacuation, said aspirator conduit being discontinuous and comprising afirst part into which fluid under pressure flows having an outletopening in communication with said chamber and a spacedly opposed secondpart having an inlet opening in communication with said chamber, theperipheral area of the inlet opening of the second part of saidaspirator conduit constituting a valve seat; a pivotally mounted thinflat flexible valve member spacedly mounted from the outlet opening ofsaid first aspirator part and arranged to seat upon the entire areaconstituting said valve seat; the outlet opening of the first part ofsaid aspirator conduit being arranged to direct a stream of fluidtowards the inlet opening of the second part; a valve operating meansconnected to said valve member and including said pressure sensitivemeans and adapted to alternately cause said valve to completely open andcompletely seal the inlet opening of the second part of said aspiratorconduit in response to predetermined pressures in said chamber; wherebywhen said valve member is seated to seal the inlet opening of the secondpart, a substantial inflow of fluid into said chamber around said valvemember is permitted but substantially no flow is permitted through thesecond part for all operating pressures.

2. A cycling valve apparatus for breathing equipment having a fluidreceiving chamber enclosed by a pressure sensitive means; an outletdelivery conduit member connecting said chamber for periodicallydelivering fluid therefrom; an aspirator assembly associated with saidchamber for periodically evacuating fluid from said cham ber, saidaspirator assembly comprising an aspirator conduit provided with aninternal restriction for creating 7 a jet stream of fluid to aid saidevacuation, said aspirator conduit being diseontinuous and comprising afirst part into which fluid under pressure flows having an outletopening in, communication with said chamber and a spacedly opposedsecond part having an inlet opening in communication with said chamber,the peripheral area of the inlet opening of the second part of saidaspirator conduit constituting a valve seat; a pivotally mounted thinflat flexible valve member spacedly mounted from the outlet opening ofsaid first aspirator part and arranged to seat upon the entire areaconstituting said valve seat; the outlet opening of the first part ofsaid aspirator conduit being arranged to direct a jet stream of fluidinto the inlet opening of the second part when the valve member isremoved from said inlet opening; a snap acting valve operating meansconnected to said valve member and including said pressure sensitivemeans and adapted to alternately cause said valve to completely open andcompletely seal the inlet opening of the second part of said aspiratorconduit in response to predetermined pressures in said chamber; saidparts of said aspirator conduit being so arranged that when said valvemember is seated, the outlet opening of said first part is spaced fromthe valve member by such a distance that a primary and substantialinflow of fluid into said chamber around said e valve member ispermitted which impinges a flowing pressure stream upon said valvemember to further insure its seating and whereby substantially no flowis permitted through the second part for all operating pressures.

3. A pressure control apparatus for use in resuscitators and the like,comprising a housing defininga fluid receiving chamber, a pressuresensitive diaphragm enclosing one Wall of said chamber, an aspiratorassembly associated with said housing into which a gas under pressureflows, said assembly including an aspirator conduit comprising a firstpart connecting with said chamber for delivering gas thereto and aspaced apart second part adjacent said first part and substantiallycoaxial therewith providing a gas outlet from said chamber connecting tothe ambient atmosphere, a valve member slidably seated upon the end ofsaid second part opposed to and spaced from the outlet of the firstconduit part, means connected to the pressure sensitive diaphragm forperiodically withdrawing said valve member into said chamber so as toopen said second part of said conduit, and means for retaining saidvalve member in seated position when the pressure within the fluidreceiving chamber is within predetermined limits, whereby when saidvalve member is seated to seal the second part, a substantial inflow offluid into said chamber around said valve member is permitted butsubstantially no flow is permitted through the second part for alloperating pressures.

4. A pressure control apparatus for use in resuscitators and the like,comprising a housing defining a gas receiving chamber, a pressuresensitive diaphragm enclosing one wall of said chamber, an aspiratorassembly associated with said housing into which a gas under pressureflows, said assembly including an aspirator conduit provided with aninternal restriction for creating a jet stream of fluid to aid theevacuation of said chamber periodically, said aspirator conduit beingdiscontinuous and comprising a first part into which fluid underpressure flows having an outlet opening in communication with saidchamber and a spacedly opposed second part having an inlet opening incommunication with said chamber, the peripheral area of the inletopening of the second part of said aspirator conduit constituting avalve seat; a pivotally mounted flexible valve member slidably seatedupon said valve seat contacting the entire area constituting said valveseat; the outlet opening of the first part of said aspirator conduitbeing arranged to direct a jet stream of fluid into the inlet opening ofthe second part when the valve member is removed from said inletopening; a snap acting valve operating means (a interconnecting saiddiaphragm and said valve member and adapted to alternately cause saidvalve to completely open and completely seal'the inlet opening ofmessage part of said aspirator conduit in response to predeterminedpressures in said chamber; whereby when said valve member is seated, theoutlet opening of said part is spaced from the valve member by such adistance that a primary and substantial inflow of fluid into'saidchamber around said valve member is permitted impinges a flowingpressure stream upon said valve member to further insure its seating andwhereby substantially no flow is permitted through the second part forall op erating pressures. 5,. The pressure control apparatus of claim 4wherein said valve operating means includes a rod reciproca'bly mountedin said housing connected to the pressure sensi tive diaphragm, meansconnected to the rod for periodi; cally pivoting said valve member intosaid chamber as to open said inlet opening of the second'p'ar't, andmeans biasing the movement of the rod so as to. restrain the rod whenthe pressure within the gas receiving chamber is within predeterminedlimits. 4

6. A pressure control apparatus for use in resuscitators and the like,comprising a housing defining a 'g' is ceiving chamber, an aspiratorassembly associated w1th said housing into which a gas underpressure'fiows said assembly including a first conduit member connect"with said chamber for delivering gas thereto and a sec} ond conduitmember adjacent said first conduit. member and coaxial therewithproviding a gas outlet from said chamber connecting to the ambientatmosphere, a pivotally mounted flexible valve member slidably seatedupon the end of said second conduit member opposed to and spaced fromthe outlet of the first conduitmemher, a pressure sensitive diaphragmdisposed in one wall of said. chamber, a rod reciprocably mounted insaidho a ing connected to the pressure sensitive diaphragm, meansconnected to the rod for periodically pivoting said valve member intosaid chamber so as to open said second conduit member, and means biasingthe move of the rod so as to restrain the rod when the pressure w thinthe, gas receiving chamber is within predetermined limits. 7. A pressurecontrol apparatus for use in resuscitat and the like, comprising ahousing defining a gas rec ing chamber, an aspirator assembly associateds'al housing into which a gas under pressure flows s aspirator assemblyincluding a first conduit member corrnecting with said chamber fordelivering gas thereto and a second conduit member adjacent said firstconduit membeer and coaxial therewith providing a gas outlet from saidchamber connecting to the ambient atm sphere, pivotally mounted flexiblevalve member slidably se upon the end of said second conduit member' adjthe first conduit member for opening and closing second conduit member,a pressure SCIlSlfiVQ diaphragm disposed in one wall of said chamber, arod, reciprocably mounted in said housing yieldingly connected to thepressure sensitive diaphragm, actuator means connected to the rod foractuating said valve member, to open and close said second conduitmember, said valve member having an aperture therein and oppositelydirected'ton e members integral therewith projecting into said ape re,so as to provide knife edges for engagement. with said actuator means,and adjustable biasing 'rneans restr" 'n'g the movement of said rod whenthe pressure withi sa gas receiving chamber is within predeterminedlimits 8. A pressure control apparatus for use in re'suscitators and thelike, comprising a housing defining a gas receiving chamber, anaspirator assembly associated with said housing into which a gas underpressure flows, said aspirator assembly including a jet deviceconnecting said chamber for delivering gas thereto and a conduit member,coaxial with said jet device providing a gas outlet from said chamberconnecting to the ambient atmos; phere, a pivotally mounted flexiblevalve memher Slidf ably seated upon the end of said conduit memberadjacent the jet device for opening and closing said conduit member, apressure sensitive diaphragm disposed in one wall of said chamber, a rodreciprocably mounted in said housing yieldingly connected to thepressure sensitive diaphragm, actuator means connected to the rod foractuating said valve member to open and close said conduit member, saidvalve member having an aperture therein and oppositely directed tonguemembers integral therewith projecting into said aperture so as toprovide knife edges for engagement with said actuator means, andadjustable biasing means restraining the movement of said rod when thepressure within said gas receiving chamber is within predeterminedlimits.

References Cited in the file of this patent UNITED STATES PATENTS704,782 Dickinson July 15, 1902 10 LaLonde May 30, 1911 Lunceford Mar.18, 1913 Rockwell Nov. 28, 1916 Rockwell Jan 2, 1917 Reedy Oct. 10, 1933Bloomheart Nov. 5, 1940 Soderberg Feb. 14, 1950 Fox Jan. 2, 1951 MuellerApr. 3, 1951 Seeler June 2, 1953 Seeler Feb. 28, 1956 Kreitchman Apr. 1,1958 FOREIGN PATENTS Switzerland July 8, 1901 Italy Nov. 22, 1928 ItalyOct. 9, 1937

